1. Technical Field
The present invention is directed to sharpening methods and apparatuses for rotary defatting knives and, more particularly, to a sharpening tool for circular blades having at least one lower blade sharpening surface and an upper blade sharpening surface disposed and supported at an angle from the lower blade sharpening surface, the lower and upper blade sharpening surfaces operative to simultaneously engage the convergent faces of the circular blade and remove metal therefrom to create a pointed edge where the convergent faces meet.
2. Description of the Prior Art
The meat packing and processing industry has become increasingly important as the world population continues to grow thereby increasing the need for meat and meat products. As a result of the increased demand for meat, the meat packing industry had to become more efficient in its meat processing and packing operations. Through the use of improved technology and xe2x80x9cassembly-linexe2x80x9d like operations, the meat industry has been able to increase the production of meat and meat products. However, the industry requires individuals to use some form of knife to remove bones and trim the excess fat from the meat. Accordingly, the meat packing industry has attempted to produce knives that allow the user to debone and trim meat faster, safer, and more economically; a long-felt-need which has yet to be fully addressed.
The prior art discloses knives that typically have a handle, a drive mechanism, and a blade. Although there are numerous types of powered knives which are used, one of the more commonly used types includes a circular blade which rotates at a high rate of speed, the blade being rotatably supported on a handle. These knives are used to remove and trim fat from the carcass by xe2x80x9cplaningxe2x80x9d the knife over the area on the carcass which is being trimmed and the spinning of the blade cuts the tissue being contacted to remove a strip from the carcass. It has been found that these types of blades are very efficient at removing tissue from the carcass, but there are inherent problems with the use of these knives that have not been solved by the prior art.
As with any knife, eventually the cutting edge of the circular blade of the knife becomes dull. This is especially true in the meat packing industry as the knives are used to cut through tough skin and sinew of the carcass. When an ordinary knife edge becomes dull, the user would merely sharpen the blade of the knife using any conventional sharpening apparatus. However, with a circular blade, the sharpening process is much more involved, and in the case of many of the types of circular blades used in the meat industry, it is often necessary to send the blade to the producing company for sharpening. Alternatively, the blade would be removed and replaced with a new blade. In the prior art, in order to change the blade, the knife would have to be replaced, as with the one-piece knife, or all the numerous screws or bolts would have to be removed. In either case, there will be a significant delay in the ability to use the knife blade. There is therefore a need for a sharpening apparatus and method which can be quickly and easily applied to the blade and permit rapid resumption of the use of the blade.
Many of the sharpening devices in the prior art are difficult and dangerous to use, as force must be applied to the sharpening stone or material to move it adjacent to the rotating blade. When the force is being applied, any slippage of the sharpening stone may bring the flesh of the user into contact with the rotating blade, thus causing a serious injury. Although other types of devices have been proposed to deal with this problem in connection with standard blades, the unique problems of the rotary blades have not yet been addressed, to the best of the inventors"" knowledge. There is therefore a need for a sharpening apparatus and method which will be usable safely and efficiently in connection with rotary blades and knives.
Therefore, an object of the present invention is to provide a sharpening apparatus for rotary knife blades.
Another object of the present invention is to provide a sharpening apparatus for rotary knife blades that allows the blade to be sharpened quickly and easily.
Another object of the present invention is to provide a sharpening method for rotary knife blades that allows the blade to be sharpened safely, quickly and easily.
Finally, it is an object of the present invention to provide a sharpening apparatus for rotary knife blades which is relatively simple to manufacture and is safe and efficient in use.
The present invention is directed to a sharpening apparatus for a rotary knife blade which includes a sharpening material support base and at least one lower sharpening device such as a metal pin mounted on the sharpening material support base. At least one upper sharpening device is mounted on the sharpening material support base, the upper sharpening device extending at an acute angle upwards above and relative to the lower sharpening device. The upper and lower sharpening devices are disposed relative to one another to generally simultaneously engage upper and lower surfaces of a blade to be sharpened and a guide device such as a curved wall structure is operative to releasably guide a blade between the upper and lower sharpening devices to assist with sharpening of a blade.
The present invention also contemplates a method which includes the steps of providing a rotary knife blade having upper and lower surfaces and a sharpened edge therebetween, at least one lower sharpening device mounted on a sharpening material support base and at least one upper sharpening device mounted on the sharpening material support base, the upper sharpening device extending at an acute angle upwards above and relative to the lower sharpening device. The sharpening material support base is then positioned adjacent the rotary knife blade while the blade is rotating and the lower surface of the rotary knife blade is engaged by the at least one lower blade sharpening device. One of the rotary knife blade and the at least one upper sharpening device are moved until the at least one upper blade sharpening device contacts the upper surface of the rotary knife blade and then the at least one upper and lower blade sharpening devices each contact one of the upper and lower surfaces respectively of the rotary knife blade generally simultaneously, thus abrading the upper and lower surfaces of the rotary knife blade and sharpening the sharpened edge.
The present invention as thus described has many advantages over those devices found in the prior art. The sharpening apparatus is designed to receive the blade therewithin and allow the operator to quickly and easily sharpen the blade. Furthermore, the construction materials used in connection with the apparatus will quickly and safely sharpen even the most difficult rotary knife blade. Additionally, the shape and design of the apparatus will generally prevent accidents during its operation. Finally, the method of sharpening rotary blades taught by the present invention renders the invention far more efficient and safe for use than those methods and devices found in the prior art. Therefore, the present invention is seen to provide substantial improvements over those methods and devices found in the prior art.